Numerous anti-theft devices have been developed for automotive vehicles. The majority of these are subject to any of various difficulties. In the first place, many are very complicated to install. In other cases, the anti-theft device is located so as to warn the thief that the car is equipped with some device. Or, the anti-theft device may prevent the vehicle from being started or driven from its parked position, again alerting the thief that the car is equipped with some anti-theft device. Where the thief is alerted to the fact that there is such an anti-theft device in the car, he is very apt to disarm the device or cause damage to the vehicle in his frustration to complete his intended theft. Where the automotive vehicles are left in remote or unattended areas, the thief has ample time to tamper with any anti-theft device or even strip the car if he is unsuccessful in starting it and driving away.
As a result, consideration has been given to anti-theft devices which allow the car to be started and which subsequently disable it. In some cases, this is done by a timing device which results in the engine being disabled a predetermined time after it is started unless some step has been taken to prevent the operation of this disabling device. In some cases, the tires have been allowed to deflate if the engine is driven by an unauthorized person. In another instance, the fuel to the engine is shut off so that after a vehicle is driven a short distance, it stops.
While all of these devices which have just been described do have the advantage that they permit the car to be started by the thief and then stop the car after it has been driven for a while, they do have various disadvantages. In some cases, such as allowing the tires to become deflated, there can be definite damage done to the car by the thief in attempting to continue to drive the car after the tires have become deflated. In other cases, the device is difficult to install or cannot be readily tested to determine whether it is operating properly.